This is a medical research study for patients with Crohn's disease intended to investigate the safety and therapeutic effect of two different doses of an antibody (a protein) against TNF compared to a placebo (inactive substance). The name of the antibody is Infliximab (Remicade). Infliximab has been developed to decrease the effects of TNF and to reduce the inflammation and ulceration of the bowel. Infliximab is a chimeric antibody which means the antibody is part mouse protein and part human protein. The goal of the study is to evaluate whether patients respond longer.